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The implementation of this project by the beneficiary entity ANFACO-CECOPESCA and its partner, the CARTIF Foundation, has made it possible to design and manufacture sustainable feed for aquaculture species, such as rainbow trout (Oncorhynchus mykiss) and sea bass (Argyrosomus regius), using alternative ingredients to fishmeal and krill oil, such as microalgae (Nannochloropsis gaditana, Tisochrysis lutea, Rhodomonas lens and Isochrysis galbana), cooking water resulting from the manufacturing processes of canned tuna and insect meal (Acheta domesticus).

The results obtained are as follows:

• Microalgae: the accumulation of lipids and omega-3 was greater in the stationary phase of culture. Even so, large-scale crops were maintained in an exponential phase by applying a semi-continuous regime. Centrifugation is also an appropriate harvesting method for a wide range of microalgae species, in terms of yield, concentration of the final product and cell integrity. In terms of protein and EPA, they have a high content. In the selection of microalgae rich in lipids and polyunsaturated fatty acids, it was decided to optimize the culture conditions and determine the optimal growth phase of accumulation of fatty acids of interest. In addition, the selection of the most efficient harvesting method was studied. The results showed that there is a variability in terms of the total amount of lipids and fatty acid profile between species and between harvest phases. The optimal culture conditions for each species were chosen in the pilot-scale culture. During this phase, 5,370 litres of microalgae have been produced, with a total of 174,469×109 cells, with an estimated production weight per hour of 14,341.8 g of harvest. These microalgae have a protein and fatty acid profile suitable for use as an ingredient in aquaculture feed.

• Tuna cooking water: the process developed for protein recovery is technically feasible. It has been shown that by employing centrifugation and nanofiltration processes, protein concentration values of 6% can be achieved, similar to that present in the tailwaters generated in fishmeal manufacturing processes. On the other hand, it is feasible to obtain an oil with a composition of fatty acids that is very suitable for use in aquaculture feed, and must be subjected to a previous refining process. The recovered lipid fraction has a high content of EPA, DHA and ARA, and the protein fraction has a high protein content. In addition, high percentages of polyunsaturated fatty acids and a high level of omega-3 and omega-6 were found, some of the essential requirements in the diet of rainbow trout and sea bass, with which the feeds formulated from the alternative ingredients obtained in the project will be validated.

• Insect meal: its quality is quite heterogeneous and depends on the species in the first place and the type of food used for its cultivation. Flours generated from A. domesticus and H. illucen contain a high protein and lipid level. Given the high level of biogenic amines present in H. illugens meal, which prevents its use as an ingredient in the fish’s diet, only the A . domesticus insect has been integrated into the feed design. The nutritional profile observed shows significant differences between the two, although they meet the expectations of the percentage of proteins, above 40%. However, the fatty acid profile is quite incomplete and the lack or low amount of EPA and DHA in the flour produced needs to be compensated.

Based on this selection and the study carried out of the nutritional requirements of juveniles of trout and sea bass, four diets were designed. In the case of sea bass, two types of feed were made, one with a diameter of 2 mm and the other of 3 mm.

The results were presented at a national congress (XXII Forum of Marine Resources and Aquaculture of the Galician Rías, held in O Grove), and at an international meeting (Business2Sea, in Porto), as well as at two dissemination days, one at ANFACO (Vigo) and another held in Cádiz, organized by Fundación Biodiversidad.